364 KUNKEL: PROMYCELIUM OF CAEOMA NITENS 
Although there is considerable variation in the length and 
shape of the promycelium when grown on various media, under 
fairly similar conditions it is rather constant both in size and in 
shape. Generally it reaches a length of three or four times the 
diameter of the spore, but sometimes it becomes much longer than 
this. The average diameter of the spore, based on a measurement 
of twenty-five spores taken at random, is twenty-one microns. 
The average length of the mature promycelium, based on the 
same number of measurements, is seventy-eight microns. 
DIscussION 
Tranzschel (9) and Clinton (2) both claim to have established 
by infection experiments that Puccinia Peckiana Howe is the 
teleutostage of Caeoma nitens. Tranzschel removed three healthy 
blackberry plants from the park of the St. Petersburg’ Forestry 
Institute. One of these plants he grew under a bell jar in the 
laboratory of the Institute; the other two plants were placed in a 
garden. The three plants were inoculated with spores of Caeoma 
nitens. Later in the season all of the three plants became infected 
with Puccinia Peckiana. Tranzschel had no control plants in his 
experiment and he makes no mention of having observed the 
plants in the park of the St. Petersburg Forestry Institute at the 
time his plants showed infection with the Puccinia. 
Clinton transplanted blackberry plants from the forest to his 
greenhouse. He inoculated two of these with the aecidiospores of 
Caeoma nitens taken from infected blackberry plants. In a 
little less than two months both of these plants showed infection 
with Puccinia Peckiana, while several other blackberry plants 
that had been used as checks showed no infection. It is worth 
noting that three raspberry plants which he inoculated with spores 
of Caeoma nitens taken from infected raspberry plants, failed to 
become infected. All plants used had been free from both the 
Caeoma and the Puccinia during the previous summer. 
It is hardly to be expected that the change from sporophyte to 
gametophyte should occur in two different places in the life history 
of the same rust, but further experiments are needed in order to 
settle this point. 
The production of a promycelium by the aecidiospores of 
